FABRICATION OF A SI1-XGEX CHANNEL METAL-OXIDE-SEMICONDUCTOR FIELD-EFFECT TRANSISTOR (MOSFET) CONTAINING HIGH GE FRACTION LAYER BY LOW-PRESSURE CHEMICAL VAPOR-DEPOSITION

A method for growing the high-quality strained epitaxial heterostructure of Si/Si1-xGex/Si by low-pressure chemical vapor deposition (CVD) and the fabrication of Si1-xGex-channel metal-oxide-semiconductor field-effect transistors (MOSFET's) with a high Ge fraction layer have been investigated. It is found that lowering of the deposition temperature of the Si1-xGex and Si capping layers is necessary with increasing Ge fraction in order to prevent island growth of the layers. With the use of the optimized fabrication process, Si/Si1-xGex/Si heterostructures with flat surfaces and interfaces were realized, and a high-performance Si0.5Ge0.5-channel MOSFET has been achieved with a large mobility enhancement of about 70% at 300 K and over 150% at 77 K compared with that of a MOSFET without a Si1-xGex channel.